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D. Stream Buffer Zones <br />The Division previously approved surface or underground mining <br />activities within 100 feet of or through a perennial stream or stream with a <br />biological community. This decision was based on a finding that the <br />original stream channel would be restored, water quality and quantity <br />would not be adversely affected, and appropriate riparian vegetation would <br />be reestablished. The buffer zone variance was granted for the former <br />water pump station on Trout Creek, and for the facilities area along Oak <br />Creek [Rule 4.05.18(1)]. For these azeas, the Division also finds that: a) <br />the surface coal mining operations will not cause or contribute to the <br />violation of applicable water quality standazds, and b) during and after <br />mining, the water quantity and quality, and other environmental resources <br />of the stream shall not be adversely affected [Rule 4.05.18(1 ]. <br />E. Probable Hydrologic Consequences (PHC) of Mining <br />Section 2.5 in Volume 3 of the PAP contains an assessment of the <br />hydrologic consequences of the Edna Mine. Those consequences (with <br />PHC page number or other reference) aze summarized below. <br />Projected Imnacts <br />Post-mining infiltration rate of meteoric water -Annually, 1.95 <br />inches of meteroic water will infiltrate from the ground surface into <br />the subsurface (PAP, page 2.5-88). <br />2. Spoil saturation -The infiltrating water will saturate spoil in the toe <br />(northwestern, down-dip end) of each backfilled pit (PAP, Exhibit <br />2.5-25). <br />3. Spoil leachate quality - As the infiltrated water percolates through <br />the spoil, it will become mineralized to form a spoil leachate <br />having an average total dissolved solids (TDS) concentration of <br />3000 mg/1(PAP, page 2.5-96). This compazes to TDS of less than <br />600 mg/1 in this stratigraphic sequence prior to mining. <br />4. Dischazge of leachate from pit -From the saturated spoil in each <br />backfilled pit, the leachate will discharge into the bedrock in the <br />walls of the toe of the pit, and to the ground surface as spoil <br />springs (PAP, Exhibit 2.5-25). <br />Leachate impacts on bedrock ground water -Leachate dischazging <br />into bedrock in the toe of the pit will not cause material damage to <br />bedrock aquifers because the bedrock receiving the leachate is an <br />unmined wedge of bedrock that would transmit the leachate less <br />C-1980-001 Permit Renewal 5 Findings Page 24 of 33 Pages <br />